Construction workers and equipment excavate the southeastern corner of the World Trade Center site on Jan. 8, 2008. About 60 truckloads of debris that could contain tiny human bone fragments have been unearthed by construction crews working on the new World Trade Center tower in recent years. That material is now being transported to a park built on top of the former Fresh Kills landfill on Staten Island. (ASSOCIATED PRESS / Mark Lennihan, File)

NEW YORK (AP) — Jim Riches pulled his son’s mangled body out of the rubble at the World Trade Center, but the phone calls still filtered in years afterward. The city kept finding more pieces of his son.

“They’ll call you and they’ll tell you, ‘We found a shin bone,”’ Riches said. “Or: ‘We found an arm bone.’ We held them all together and then we put them in the cemetery.”

Those are the phone calls both dreaded and hoped for among the families of Sept. 11 victims. And as investigators began sifting through newly uncovered debris from the World Trade Center this week for the first time in three years, those anxieties were renewed more than a decade after the attacks.

But there was also hope that more victims might yet be identified after tens of millions have been spent on the painstaking identification process. Two potential human remains were recovered on Monday, according to the medical examiner.

“We would like to see the other 40 percent of the families who have never recovered anything to at least someday have a piece of their loved one,” Riches said. “That they can go to a cemetery and pray.”

About 60 truckloads of debris that could contain tiny fragments of bone or tissue were unearthed by construction crews that have been working on the new World Trade Center in recent years. That material is now being transported to a park built on top of the former Fresh Kills landfill on Staten Island, where investigators will attempt to find any possible remains during the next 10 weeks, the city said. That’s the material the two potential human remains were found in.

The city’s last sifting effort ended in 2010. This time, crews were able to dig up parts of the trade center site that were previously inaccessible to workers, the city said.

Some 2,750 people died at the World Trade Center in the 2001 terrorist attacks, but only 1,634 people have been identified.

“We have been monitoring the World Trade Center site over time and monitoring the construction,” said Ellen Borakove, a spokeswoman for the medical examiner’s office. “And if they see any material that could possibly contain human remains, we collect that material.”

About 9,000 human remains recovered from the ruins of the World Trade Center remain unidentified because they are too degraded to match victims by DNA identification. The remains are stored at an undisclosed location monitored by the medical examiner’s office and will eventually be transferred to a subterranean chamber at the National September 11 Memorial & Museum.

Some victims’ families expressed impatience that the city has only just uncovered more debris.

“Quite frankly, they should’ve excavated this and searched it 12 years ago,” said Diane Horning, whose son, Matthew, died in the attacks. “Instead, they built service roads and construction roads and were more worried about the building and the tourism than they were about the human remains.”

The city’s efforts to identify Sept. 11 victims have long been fraught with controversy.

In April 2005, the city’s chief medical examiner, Charles Hirsch, told families his office would be suspending identification efforts because it had exhausted the limits of DNA technology.

But just a year later, the discovery of human remains on a bank tower roof and then in a manhole near ground zero outraged families who said the search for their loved ones had been rushed initially. The findings prompted a renewed search that cost the city tens of millions of dollars and uncovered 1,500 pieces of remains.

Meanwhile, some victims’ relatives sued the city over its decision to move 1.6 million tons of materials from the trade center site to the Fresh Kills landfill, saying the material might contain victims’ ashes and should have been given a proper burial.

The lawsuit was dismissed, and unsuccessfully appealed to the U.S. Supreme Court.

As it embarks on combing through debris yet again, the medical examiner’s office says it will keep monitoring the site as long as new areas are being dug or exposed.

Charles G. Wolf was pleased to hear about the renewed search, though he believes that his wife, Katherine, was vaporized during the attack. Investigators have never found her remains.

Years ago, it bothered him that he had no grave to visit. Wolf said the opening of the Sept. 11 memorial has filled a hole in his heart, but he’ll never have closure.